The present invention is generally related to the creation of markers on sheet-type work material, and is more specifically directed to analyzing and compensating for the distortion in patterns defined by said work material as a result of being spread onto a support surface prior to the performance of a work operation.
The present invention is particularly well suited for use in the creation of markers generally utilized in the production of garments and will be explained in connection with such use. However, the present invention is not limited in this regard as any application wherein pattern bearing sheet material is spread resulting in some distortion of the pattern, such as in the cutting of fabric to upholster furniture, can benefit from the present invention. Accordingly, the following descriptions of the present invention should be considered as illustrative, and not limiting.
In the mass production of garments, one or more layers of fabric are typically spread onto what is referred to by those skilled in the art of fabric processing as a spreading table. The fabric is then moved, often via a conveyor, onto a support surface forming part of a fabric processing apparatus such as cloth cutting machine. During the spreading and subsequent movement of the fabric on to the processing apparatus, some stretching and distortion often occurs. This is especially problematic when the fabric defines a pattern as any pattern pieces cut from the stretched and distorted fabric without compensating for the malformation will likewise have the pattern distorted therein.
Generally, pattern pieces are positioned on the spread fabric in a spatial array of garment segments positioned in a cutting sequence. This spatial array of garment segments is referred to by those skilled in the pertinent art to which the present invention pertains as a xe2x80x9cmarker.xe2x80x9d Usually markers are computer generated to optimize piece pattern density and thereby minimize the waste of fabric or other spread material. In the past, computerized marker systems simply generated a marker having fairly large tolerances between adjacent pieces. The spread was first cut such that the pieces to be matched were cut including the aforementioned tolerances. These pieces were then provided to a skilled worker who would manually align the several patterns with the geometric spread design and thereafter re-cut the matched pieces. Spreads that have a geometric pattern such as plaids or stripes also caused difficulty because the clothing designer could specify an alignment of the pattern in several adjacent pieces. As a result, pieces cut from a spread having a geometric design invariably mandate higher costs due to increased waste and the use of slow, skilled labor in the cutting process.
Prior art attempts to perform machine assisted matching whereby a match image overlays a reference image and requires operator assistance to visually align the patterns leads to difficulty in alignment when the bow/skew of the fabric at a reference point is different from the bow/skew of the fabric a point that must be matched to the reference point.
Furthermore, algorithms for automatic pattern matching are well suited to cases when the image to search contains an undistorted version of the image to find. Attempting to account for image distortions in the automatic matching process increases the complexity and time consumption of the matching algorithms. Distortions may also reduce the probability that a matching algorithm will succeed.
Attempts at automatic matching between spread fabric and pattern pieces whereby a match point is restricted to adjustment in only one coordinate direction have also been made. In this instance it is possible for a seemingly correct match point to result in an incorrect adjustment to a marker. To illustrate this problem, reference should be had to FIG. 1, wherein two pattern pieces, a reference piece and a match piece are shown. The match piece is shown in the unmatched position. A picture is taken at reference point xe2x80x9cRxe2x80x9d on the reference piece, and a subsequent picture is taken at match point xe2x80x9cMxe2x80x9d on the match piece. A computer processor then analyzes and compares the two images. The objective is to move the match piece so that it matches the pattern defined within the periphery of the reference piece. The automatic matching routine will return point xe2x80x9cAxe2x80x9d, FIG. 1, as the corrected match point for reference point xe2x80x9cRxe2x80x9d. Since the automatic matching routine allows for movement of the match piece in only a single coordinate direction, in this case the direction labeled xe2x80x9cXxe2x80x9d in FIG. 1, the match piece will be moved in the X direction such that point xe2x80x9cMxe2x80x9d overlays point xe2x80x9cA1xe2x80x9d. Based on the pattern defined within the periphery of FIG. 1, the correct match point is xe2x80x9cA2xe2x80x9d and therefore the automatching technique described fails to properly align point xe2x80x9cMxe2x80x9d with point xe2x80x9cRxe2x80x9d.
Based on the foregoing, it is the general object of the present invention to provide a method for compensating for pattern distortion on sheet-type work material spread onto a support surface that overcomes the problems and drawbacks of prior art methods.
The present invention is directed in one aspect to a method for compensating for pattern distortion on sheet-type work material spread onto a support surface wherein a work material processing apparatus defining the support surface is provided. At least one layer of work material is spread onto the support surface and images of areal portions of the work material in the spread condition are captured via means provided. These means capture images corresponding to the locations where pattern pieces making up markers will be positioned and transmit signals corresponding to the captured images to a controller in communication therewith.
The controller is programmed with the marker configuration, as well as to analyze distortion in the pattern defined by the spread work material. A display in communication with the controller receives signals from the controller and projects images thereon corresponding to those captured. The distortion of the pattern shown in the captured image is then mapped so that the controller can analyze the extent of the distortion thereon. The mapped image of the distorted pattern is then undistorted via the controller and an undistorted image is projected onto the display. Undistorted digital representations of the pattern pieces that will comprise the marker are then positioned by an operator on the undistorted image of the spread work material to align the pattern defined within the boundary of the pattern piece with that corresponding to the image of the spread work material shown on the display. Once the pattern pieces are positioned, the controller operates to distort the geometry defined by the pattern pieces relative to the actual distortion of the pattern defined by the areal portions of the work material upon which the pattern piece is positioned so that when the pattern pieces are cut from the spread work material the pattern contained therein will be undistorted.
In the preferred embodiment of the present invention, the means for capturing an image of the work material when spread onto the support surface is a camera. Preferably, the support surface is approximately flat with the camera coupled to a beam extending transversely across the support surface. The beam is movable, back-and-forth in a direction longitudinal of the support surface with the camera being movable longitudinally along the beam.